Generally, bleaches are classified into chlorine-based bleaches and oxygen-based bleaches. The chlorine-based bleaches have limitations in the use thereof since they decolorize the dyes of clothes or have a unique irritating odor. Thus, the oxygen-based bleaches without such drawbacks are generally used as bleaches or detergents for clothes.
For the oxygen-based bleaches, liquid hydrogen peroxide has long been used in liquid bleaches, and solid sodium perborate (NaBO3.H2O, NaBO3.4H2O) and sodium percarbonate (2Na2CO3.3H2O2) have long been used in powder bleaches or detergents. However, oxygen-based bleaches, such as sodium perborate, sodium percarbonate and hydrogen peroxide, are inferior in bleaching ability to the chlorine-based bleaches and have relatively low bleaching performance at low temperature, and thus, can exhibit a sufficient bleaching effect only at a temperature of more than 60° C. If these inorganic peroxides are used at a lower temperature than 60° C., their oxidizing ability can be enhanced by the addition of bleach activators, such as acyls or esters. However, such prior bleach activators are disadvantageous in that they should be generally compounded in stoichiometrically equal or greater amounts. Furthermore, the prior bleach activators have a disadvantage in that their efficiency is remarkably reduced at a washing temperature of about 20° C., which is the washing environment in Korea.
It has been known in the prior art that general transition metal ions catalyze the decomposition of hydrogen peroxide and a peroxide generating hydrogen peroxide in an aqueous solution. In view of this fact, there have been efforts to solve the problem of the prior bleach activators and to develop effective bleach activators which can show sufficient bleaching ability even at a low temperature of about 20° C. U.S. Pat. Nos. 4,119,557 and 4,430,243 disclose methods of using transition metal ions together with chelating agents, to activate peroxide. However, all combinations of transition metal ions and chelating agents are not regarded to be effective in activating the oxygen-based bleaches. It is known in fact that many combinations of transition metal ions and chelates have no bleaching effects or show adverse effects.
Accordingly, in order to use transition metals as activating catalysts in bleaching compositions and bleaching detergent compositions, it is particularly important to find out metal catalysts which do not cause irreversible oxidations and decompose peroxides in only a pathway of bleaching.
In this viewpoint, attempts to use transition metal compounds, particularly complexes comprising manganese and cobalt, as bleaching catalysts, are recently made. For example, U.S. Pat. No. 5,246,621 discloses a binuclear manganese complex with a 1,4,7-trimethyl-1,4,7-triazacyclononane ligand. This transition metal complex can be used to wash fabrics using suitable inorganic peroxides. However, this complex has problems in that it is very expensive due to a difficult synthesis thereof, and causes excessive bleaching to damage fibers or to decolorize dyes, when the catalyst is used in an excessive amount. In the usual laundry practice of customers, a detergent is put onto the laundry to which water is then added. Thus, an excessive amount of the detergent component can exist on a portion of clothes, in which case if an excessive amount of the bleaching catalyst exists to cause excessive bleaching, fiber damage or dye fading can occur.